SEVASTOPOL, Ukraine – A Ukrainian officer at a military base in Ukraine's region of Crimea says that pro-Russia soldiers have crashed a truck through its gates in an attempt to take it over.

Lt. Col. Vitaly Onishchenko, deputy commander of the base, said three dozen men wearing unmarked camouflage uniforms arrived late Friday. He said Saturday they turned off power and cut telephone lines and urged Ukrainian troops surrender their weapons and swear allegiance to Russia. The invaders left around midnight.

No shots were fired, but the incident reflected tensions running high in Crimea, where Ukrainian military bases have been seized or blocked by pro-Russia forces. Russia has a major naval base in Crimea.

Crimea's parliament has set a March 16 referendum on joining Russia, which has been denounced by Ukraine's government.